1. Technical Field
The present invention relates to a method for adhering three-dimensional bits, fragments, chunks, or morsels to a substrate and more particularly, to a method for adhering large three dimensional food bits to a snack food substrate whereby the large bits are substantially adhered to the substrate. More specifically, the present invention relates to a method for making a dual-textured, topped snack food.
2. Description of Related Art
Food particulates are often added to foods, especially snack foods. Tortilla chips, pretzels, crackers, popcorn, and numerous other foodstuffs often have seasonings applied to them during processing. Seasonings used, usually in a powdered form, have included salt, cheese, chili, garlic, Cajun spice, ranch, sour cream and onion, among many others. However, there is often an undesirable accumulation of seasoning on the sidewalls and bottom of the snack food bag with the result that the consumer has less than the desired complement of topping thereon. The separation occurs because of insufficient adhesion of the seasoning to the chip. The problem of separation increases with the size and weight of the individual particles.
One way this problem has been approached in the past was by using oil as an adhesive to adhere particulate seasonings to a base or substrate. For example U.S. Pat. No. 6,534,102 B2, issued to Kazemzadeh, discloses a seasoning bit that, following extrusion and cooking is immersed into an oil and seasoning slurry at an elevated temperature. The product is then dry-coated with seasonings or sprayed with hot or room temperature oils and fats either carrying seasonings or the seasonings are applied as dusting on the surface while the oil and fats are used to adhere the seasoning to the surface. One drawback to using only oil, however, is that the adhesive strength of traditional oil mixes are not strong enough to adhere large three-dimensional bits to a substrate surface. In certain applications, large three-dimensional bits are desirable because they enable packaged snack chips to emulate another topped product including, but not limited to a pizza with toppings, a nacho chip, or a tostada.
Another prior art composition used to adhere particulate to a food product is U.S. Pat. No. 3,689,290 issued to Blackenstock et al which discloses using a coating agent comprised of dry corn syrup solids to adhere small particle sizes of food toppings to a substrate. The Blackenstock Patent discloses a particle size of the food topping as being 12–100 mesh, which corresponds to a particle size range of 0.150 to 1.68 millimeters (0.0059 to 0.0661 inches). Again, these are relatively small particle sizes that are being adhered to a substrate. The adhesive is not strong enough to adhere a substantial amount of larger three-dimensional particles to the chip.
U.S. Patent Application 2002/0187220 A1 discloses an edible particulate adhesive comprising maltodextrin, an edible surfactant, a solvent, a polysaccharide, and a modified starch. The invention, however, is clearly aimed at very small particulate adhesion. The invention indicates the preferred particle size is less than 650 micrometers. Thus, this invention also fails to adhere relatively large bits to a chip.
Another prior art composition used to adhere flavorings to a foodstuff is illustrated by European Patent EP 0 815 741 A2 which discloses a hot melt composition comprising a starch, such as corn syrup, maltodextrin, or an amylase-treated starch, and a plasticizer, such as a polyol or a polyacetic acid. Like the other inventions, this invention was also designed to adhere powdery-type particulate additives to foodstuffs such as salt, sugar, cheese powder, and ranch seasonings. Like other inventions in the prior art, it also fails to adhere relatively large bits to chips.
Another prior art approach to adhere large food flavorings and spices was to put the flavorings on an unbaked cracker. Thus, cheese flavorings and other spices were then baked into the dough. This approach, however, cannot be used when it is desirable to adhere particles to a substantially cooked snack piece, such as a tortilla chip, immediately prior to the addition of seasoning.
Consequently a need exists for a method to adhere large particulate flavoring bits, fragments, chunks, or morsels to a food substrate. The method should allow a snack food to demonstrate the characteristic look, texture, and taste of an emulated topped food product, yet be highly resistant to separation. The method should be adaptable to a product line wherein the addition of the large particles occurs at a step after substantial cooking of the underlying food substrate.
Food ingredients are typically enclosed in a hermetically sealed food package and thus approach equilibrium with the relative humidity of the inside of the package. It has proven difficult to achieve a dual-textured or multi-textured snack food, because the food ingredient having a lower moisture content and thereby crispy texture, typically absorbs evaporated moisture from a food ingredient having a higher moisture content and thereby softer texture.
As the lower moisture content food ingredient absorbs water it becomes less crispy. As the higher moisture content food ingredient loses water, it hardens. Because of this moisture migration it is difficult to achieve a long shelf-life on dual textured snack products.
The water content of a food ingredient is typically measured by its water activity level (“Aw”). The Aw is defined by the following equation:Aw=P/Po                where P=vapor pressure of water in the food         Po=vapor pressure of pure water under the same conditions.        
The Aw is a quantitative measure of unbound free water in a system that is available to support biological and chemical reactions. Two different food ingredients with the same water content can vary significantly in their Aw level depending on how much free water is in the system. If a higher moisture content, soft texture ingredient has an Aw that exceeds the relative humidity of its environment, then water tends to evaporate from the food ingredient causing the ingredient to harden. Similarly, if a lower moisture content, crispy texture has an Aw that is less than the relative humidity of its environment, then it tends to absorb water, causing the ingredient to soften. For example, consider a piece of soft cheese, having an Aw of 0.92 placed on a crispy cracker having an Aw of 0.10 in a sealed container initially at 50% relative humidity. Over time the texture of the soft cheese hardens as it loses water and approaches equilibrium with the container atmosphere. The texture of the crispy cracker, however, softens as it absorbs this evaporated moisture to approach equilibrium with the container atmosphere. As a result, both food ingredients lose their desired texture. Moreover, besides texture changes, changes in moisture can lead to other undesirable effects including microbial growth, degradation reactions, and organoleptical changes.
The problem is compounded in multi-textured, topped food products that require an adhesive. Water-based adhesive systems utilized on a food substrate negatively impact texture as hydration and subsequent thermal drying destroy internal structures. Moreover, a water-based adhesive deteriorates chip crispness, especially if applied in an aqueous state, because of moisture migration from the adhesive into the food substrate. In addition, there is flavor loss that results from drying a moistened food substrate. As discussed previously, oil-based adhesives fail to adhere large bit particulate flavoring bits to a food substrate. As a result, it has long been difficult for food product manufacturers to package multi-textured food products for extended shelf life storage. Numerous attempts to preserve dual-textured features of food products are illustrated in the prior art.
U.S. Pat. No. 4,401,681 discloses a method for preventing moisture migration from a high-moisture phase to a low-moisture phase. For example, the patent discloses combining corn syrup solids having a Dextrose Equivalent of 22 to 24 and a high methoxyl pectin with a pizza sauce to prevent moisture from the sauce from migrating into the pizza crust during shelf life. This disclosure, however fails to teach a method that minimizes moisture transmission from a softer texture to a crisper texture through an area having a headspace. Rather the disclosure is limited to providing a direct barrier layer between two ingredients with high differential moisture contents.
U.S. Pat. No. 4,853,236 discloses a shelf-stable dual-textured food product having a first, hard texture comprising a fruit composition on a shell portion, and a second, variably textured core portion comprising an oil-in-water emulsion. This disclosure fails to teach both an outer chewy and an outer crispy texture of a topped food product.
U.S. Pat. No. 4,961,942, discloses a dough composition having a plurality of shelf-stable textures. The patent further discloses a soft, chewy filler cookie dough and a firmer outer casing dough wherein the casing dough comprises a high sugar content. It fails to disclose a dough that can be used in savory snacks.
U.S. Pat. No. 4,913,919, assigned to the same assignee of the present application, discloses a coating composition comprising a high solids content aqueous suspension, having a solids content of at least 40% by weight. The outside surface of a snack food is coated with the aqueous solution. The coating is dried to provide a crisp outer texture and chewy inner texture. This disclosure fails to teach an outer chewy texture.
U.S. Pat. No. 5,405,625, discloses a cheese filled snack product having a crisp outer casing comprising potato flakes and pre-gelatinized rice flour. In one embodiment, the filling is moist and the snack food product can be baked or microwaved without the cheese filling over expanding or leaking. This disclosure fails to teach an outer chewy texture.
U.S. Pat. No. 6,500,474 discloses using a heated liquid coating to further coat a pre-coated food product and subsequently contacting the liquid-coated pre-coated food piece with a chunky particulate matter to form a food product enrobed with a substantially continuous chunky coating. This disclosure fails to teach an outer crispy texture.
Accordingly, a need exists for a method for making a shelf-stable dual-textured, topped snack food product comprising a crisp food substrate and a chewy topping. The method should utilize a non-water based and non-oil based adhesive that can adhere large particulate flavoring bits to a substantially cooked, crisp food substrate. The method should minimize the water activity in food product ingredients and should minimize moisture migration from the chewy topping to the crisp food substrate.